This invention is generally directed to imaging members, and more specifically, the present invention is directed to single and multi-layered photoconductive imaging members with a hole blocking layer, which is typically a thin crosslinked silane coating, or an undercoat layer (UCL) comprised of, for example, a metal oxide, such as titanium oxide dispersed in a phenolic resin/phenolic resin blend or a phenolic resin/phenolic compound blend, and which layer can be deposited on a supporting substrate; a charge generation layer and a charge transport layer which contains a polymeric acid or a copolymer solid acid. In embodiments the photoconductive imaging members can be in a number of different forms, such as in a rigid form, a drum configuration, a web, a flexible belt configuration, which may be seamed or seamless, and the like. More specifically, for the multi-layered photoconductive imaging members, the hole blocking layer in contact with the supporting substrate can be situated between the supporting substrate and the photogenerating layer, which is comprised, for example, of the photogenerating pigments of U.S. Pat. No. 5,482,811, the disclosure of which is totally incorporated herein by reference, especially Type V hydroxygallium phthalocyanine, and generally metal free phthalocyanines, metal phthalocyanines, perylenes, titanyl phthalocyanines, selenium, selenium alloys, azo pigments, squaraines, and the like. The charge transport layer comprised of charge transport materials and binders is doped by solid acids to achieve high application performance.
The imaging members of the present invention in embodiments exhibit excellent photosensitivity; desirable low dark decay characteristics; steep photo induced discharge curves; low discharge residuals and substantially little or no cycle up is needed; cyclic/environmental stability; low and excellent Vlow, that is the surface potential of the imaging member subsequent to a certain light exposure, and which Vlow is about 25 to about 100 volts lower than, for example, a comparable imaging member; low depletion potentials; high photoinduced discharge curve sensitivity. The photoresponsive, or photoconductive imaging members can be negatively charged when the photogenerating layers are situated between the charge transport layer and the hole blocking layer deposited on the substrate.
Processes of imaging, especially xerographic imaging and printing, including digital, are also encompassed by the present invention. More specifically, the layered photoconductive imaging members of the present invention can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein charged latent images are rendered visible with toner compositions of an appropriate charge polarity. The imaging members are in embodiments sensitive in the wavelength region of, for example, from about 500 to about 900 nanometers, and in particular from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source. Moreover, the imaging members of this invention are useful in color xerographic applications, particularly high-speed color copying and printing processes.